1. Field of the Invention
This invention relates to the mechanical arts. In particular, this invention relates to a latch with sensor that releasably engages a keeper, for securing two members, typically aircraft panels, to one another.
2. Discussion of the Related Art
Various types of latches join and lock aircraft panels, such as, aircraft cowlings, to one another. A typical latch includes a hook mounted to one aircraft panel that engages a keeper mounted to another aircraft panel. Further, the latch includes a handle to actuate the hook. The latch secures the aircraft panels to one another when the handle is in the closed position and the hook is engaged with the keeper. When the handle is in the closed position, the handle should be flush with the exterior surface of the aircraft panel to provide a visual indication that the latch is closed.
A problem with these latches is that, even when the handle is in the closed position, the hook may not be engaged with the keeper. For example, the hook or the keeper could be missing or broken. Unfortunately, the ground crew inspecting the aircraft cannot visually verify whether the hook has engaged the keeper to ensure the latch is properly closed. Various types of special devices, such as, a feeler mechanism, have been utilized with these types of latches to provide a visual indication of the hook and keeper engagement. Feeler mechanisms are typically mounted to the hook and detect whether the hook has engaged the keeper. If the hook does not engage the keeper, the feeler mechanism is translated to a blocking position which prevents the handle from closing. Thus, the handle is not flush with the exterior surface of the aircraft panel providing a visual flag that the latch is not properly closed. On the other hand, if the hook does engage the keeper, the feeler mechanism is translated to an unblocking position allowing the handle to close.
FIG. 1A is a side view of a prior art latch 2 properly engaged to a keeper 3, particularly illustrating a feeler mechanism 4 in the unblocking position. The latch includes a handle 5, a spring 8, a trigger lock 6, pins 10 and 11, and a hook 7. The hook includes a hooked end 9 for engaging the keeper. The handle is moveable between a closed position and an open position, with the spring biasing the handle towards the open position.
The feeler mechanism 4 fits over the hook 7 and slides relative to the hook. The feeler mechanism is generally U-shaped in cross-section and has a pair of hooked portions 13. The hooked portions align with the hooked end 9 of the hook. The feeler mechanism includes a notch 14 that cooperates with a handle pin 15 mounted to the handle 5. The feeler mechanism also includes a pair of slots 16 and 17 that align with and enclose the pins 10 and 11, respectively, which extend transversely through the hook. The slots allow the feeler mechanism to slide along the hook. The feeler mechanism further includes a pair of the secondary springs 18 and a pair of posts 19 that extend perpendicularly from the feeler mechanism. The secondary springs couple each pin with each post, respectively. The secondary springs bias the feeler mechanism towards the blocking position.
When the latch 2 is properly closed, the hooked end 9 and the hooked portions 13 engage the keeper 3 resulting in the feeler mechanism 4 sliding longitudinally relative to the hook 7 opposing the spring action of the secondary springs 18. The feeler mechanism slides to the unblocking position such that the notch 14 aligns with the handle pin 15. Then the handle pin falls into the notch allowing the trigger lock 6 to engage the protruding ends of the pin 10 and allowing the handle 5 to pivot to the closed position. In the closed position, the handle is flush with the exterior surface of the aircraft panel. Therefore, the feeler mechanism allows the handle to close, providing a visual indication that the hook has engaged the keeper and that the latch is properly closed.
FIG. 1B is a side view of the prior art latch 2 disengaged from the keeper 3 illustrating the feeler mechanism 4 in the blocking position. When the hooked end 9 and the hooked portions 13 do not engage the keeper, the feeler mechanism does not slide longitudinally relative to the hook. The secondary springs 18 then bias the feeler mechanism to the blocking position. In the blocking position, the handle pin 15 does not align with the notch 14, thus preventing the handle pin from falling into the notch. Therefore, the trigger lock 6 cannot engage the pin 10 and the handle 5 cannot pivot to the closed position. The spring action of the spring 8 then pivots the handle away from the exterior surface of the aircraft panel, towards the open position, such that the handle is angled relative to the aircraft panel. Therefore, the feeler mechanism, through the position of the handle, provides a visual indication that the hook has not engaged the keeper and that the latch is not properly closed.
Unfortunately, the prior art latch with the feeler mechanism suffers from certain disadvantages. Because pins extend through the hook to accommodate the feeler mechanism, the flight load capabilities of the latch are limited. Furthermore, the feeler mechanism is complex and uses many different parts. The feeler mechanism requires a specialized form fitting sheet metal part having many different surfaces and slots, along with secondary springs, all of which must cooperate with existing structures on the latch. For example, the notch must cooperate with the handle pin. This results in a latch that is relatively heavy and complex.
In view of the above, it should be appreciated that there is a need for a latch with sensor that provides a visual indication of the engagement of the hook and keeper, is mounted independently of the hook, and that is relatively light in weight and simple in design. The present invention satisfies these and other needs and provides further related advantages.